1. Field of the Invention
The present invention relates generally to sources of renewable energy, and more particularly to a system for harnessing tidal energy, for example to generate electricity or other forms of energy, whether directly or indirectly.
2. Description of the Prior Art
Due to the limitations of non-renewable energy sources, such as oil and coal, as well as the negative environmental effects of such energy sources, a need exists for the provision of alternative energy conversion and transfer systems that are based on renewable sources of power. At the present time, there is increasing interest in renewable energy sources such as solar, wind, wave and tidal power.
The tremendous growth in renewable energy over the past several years is well documented and the rate of growth continues to increase each year. With worldwide awareness of the negative environmental impacts of fossil fuels on our global environment, growth in the use of renewable energy appears to be constrained only by the ability to produce and deliver it at an economic price. Wind power, for example, has now entered the mainstream and has been the fastest growing segment of the energy industry over the last several years. Despite the current movement supporting renewable energy sources, many legislators and policy-makers are attempting to meet these demands through projects which relate solely to wind and solar power generation, and do not address renewable energy produced from water.
This lack of attention to water as a source of renewable energy is short-sighted. Ocean and tidal currents are capable of providing a virtually inexhaustible supply of emission-free renewable energy. Since ocean and tidal currents exist everywhere in the world, converting the energy in these currents to electricity could provide a predictable and reliable supply of electricity to the electric power systems of remote sites in many parts of the world. Since some seventy percent of the world's population lives within about 200 miles of an ocean, ocean current energy and ocean tidal energy could become a vital part of the world's energy future. There are countless numbers of island communities where ocean currents accelerate around and between land masses. These coastal communities could easily benefit from the use of ocean power. With its vast and geographically dispersed resources, ocean current energy and its associated tidal energy have the potential of becoming the next “wind” of renewable energy.
Numerous schemes for harnessing tidal power have also been developed over the years. Tidal power devices offer advantages over wave power devices. Tides are regular and predictable, whereas wave power depends essentially upon weather conditions. Another advantage of tidal power devices is the fact that less complex structures can be employed at coastal sites, because locations for tidal devices are generally exposed to less extreme weather so that the devices do not have to be constructed to the same level of survivability as ocean wave power devices.
In the past schemes, for harnessing “water power” as energy sources have typically involved water storage systems. Current methods for accumulating and preserving water supplies include storage systems, such as dams, levies, basins, wells and reservoirs. However, these storage systems are not sufficient to meet the ever increasing needs of the world's population. As a result, renewable water and energy shortages are now commonplace, and plans for future needs are problematic. Other of the previous attempted solutions for water based renewable energy systems have included systems for distributing water between reservoirs. One example is the Blenheim-Gilboa pumped storage power project located in the Catskill Mountain region of the United States. This system uses a reservoir system capable of generating electricity in peak demand periods by drawing water from Schoharie Creek and recycling it between two huge reservoirs. However, this project involves the use of a traditional hydroelectric facility which would not be economically feasible for many underdeveloped parts of the world.
WIPO Publication No. WO9721922 to Curtui, entitled “Total Electric Water System,” published Jun. 19, 1997, discloses a reservoir system with multiple segments of piping placed in series, wherein a lower elevation is reached by distributing water from a higher elevation. The water is directed out of the pipeline system and becomes a source of water at a lower elevation or is directed to areas with a water deficit. The pipeline system is made up from one or more units set downwardly each unit in connection with the other.
U.S. Pat. No. 4,192,627 to Casebow entitled “Apparatus for Generating Electrical Power” issued Mar. 11, 1980, discloses a system designed to maintain constant head pressure to achieve continuous electrical power generation. The system employed uses interconnected reservoirs for the purpose of generating electrical power.
U.S. Pat. No. 6,792,753, to Hastings, issued Sep. 21, 2004, shows a system for generating power, including a barrier partially dividing a body of water subject to tidal effects into two regions of water such that said regions of water have differing water levels over a tidal cycle. A passage is provided in the barrier for placing the regions of water in fluid communication with each other; and means are also provided within said passage responsive to flow of water for driving a power generator. Water flows from one of the regions of water to the other of the regions of water via said passage when the regions have differing water levels during a tidal cycle.
U.S. Pat. No. 7,795,749, to Weber, issued Sep. 14, 2010, shows a hydroelectric generating system coupled to a primary tidal reservoir through a bi-directional tideway to power a primary turbine as a diurnal cycle tide waxes and wanes. A secondary tidal reservoir includes a tideway and secondary turbine with flow modulated by a graduated control of a sluice gate to proportionately blend reserve tidewater capacity of the secondary tidal reservoir as a delayed resource of virtual tidal influx and reflux. An aggregate summation of tidal energy acting upon the turbine driven generators delivers a constant flow of electric power throughout the diurnal tidal cycle. Shunting excess tidal energy around the turbines during periods of reduced power-demand supplements tidal resources in subsequent phases of the diurnal tidal day when solar-day related power-demand may increase.
U.S. Patent Publication No. 2009/0322091, to Jack, published Dec. 31, 2009, describes a tidal power apparatus which includes a moored pontoon (1) having a duct (2) therethrough opening at opposed ends of the pontoon. The duct has a vertical axis rotor (3) therein driving an electrical generator (6). A deflector vane (8) is located in the duct at each end thereof, each deflector vane being mounted to pivot about a vertical axis between an active position, in which the deflector vane deflects water flow to one side of the rotor axis to cause rotation of the rotor, and an inactive position substantially aligned with the water flow from the turbine.
The above references are merely intended to be representative of the current state of the art in water storage and tidal energy devices and methods, which, despite various advances, continue to present the need for a system and method for efficiently producing a renewable water based energy supply, which supply may be distributed based on daily, seasonal, cyclic and/or regional water and energy related demands.